In many wireless telecommunication systems, system information is broadcast i.e. system information is transmitted from a transmitter (e.g. a base station) forming part of the network for receipt by any appropriate device in range of the transmitter. Typically, this information is information that is common to all appropriate devices within range; thus, it can be sent using a broadcast service. System information is typically information about the system and the serving cell that is sent by the network in a point-to-multipoint manner; that is the information is broadcast for receipt by all appropriate devices within range of the transmitter.
The transmitter may use various techniques for transmitting the system information. For instance, the transmitter may use diversity techniques. Diversity techniques are used to provide a receiver with several replicas of the same information-carrying signal. The information signals are affected when they traverse paths and these signals can be combined at a receiver within a receiving device to provide a diversity gain. Typical diversity techniques use spatial diversity (e.g. where more than one antenna is used to transmit and/or more than one antenna is used to receive a signal) or time diversity (e.g. where the same data is transmitted multiple times or a redundant error code is added or bit-interleaving is used, so that error bursts may be spread in time) or a combination of the diversity techniques (e.g. spatial and time).
One example of a diversity technique is known as Space Time Transmit Diversity (STTD). STTD provides diversity by transmitting the signal from two different antennas (spatial diversity), each having the same information but coded differently (typically coded orthogonally) (time diversity). Using STTD the decoding in the receiver of the user equipment becomes more reliable as STTD provides two kinds of diversity: the physical separation of antennas provides space diversity and the time difference derived from a bit-reversing process provides for time diversity.
The receiving device (also known as User Equipment (UE)) receives both signals but with uncorrelated fading. The UE receiver demodulates each path, summing the two block encoded bits.
One application that may use diversity techniques such as STTD is the Universal Mobile Telecommunications System (UMTS) of Third Generation (3G) telecommunications and it is in this field that the present idea will be described. However the technique is applicable to other telecommunications technologies that are emerging and to other diversity techniques (e.g. spatial, time or a combination of the two). For more information on STTD in the 3G field the reader is referred to the Standard Specification 3GPP 3G TS 25.211 v 5.0.0 (hereinafter referred to as the 25.211 standard), and in particular Section 5.3.1.1.1 (STTD) and Section 5.3.3.3 (PCCPCH with STTD encoding). For a more thorough description of system information as used in UMTS, the RRC specification 3GPP TS 25.331, v 5.0.0 (or updated versions) should be consulted, in particular Table 8.1.1: Specification of system information block characteristics. New system information blocks may be added in the future.
There are thus proposed strategies for an apparatus and a method for handling system information in wireless telecommunications system user equipment. A number of such strategies are detailed below.
Other aspects and features of the proposed strategy will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments.
The same reference numerals are used in different figures to denote similar elements.